1. Technical Field
The present disclosure relates to a variable capacitance device, and to a method of varying the capacitance of a variable capacitance device.
2. Discussion of the Related Art
Variable capacitance devices are used in a variety of applications, such as in the tuning circuits of voltage or digitally controlled oscillators used in wireless communication systems. It is often an aim of such variable capacitance devices to have a very fine step size between each capacitance value. In particular, in some applications it is desirable to attain a step size as low as 1 aF (AttoFarad, equal to 10−18 Farads).
However, existing solutions of variable capacitor devices are generally unable to achieve such a low step size, and/or they are unable to maintain such a low step size over a range of operating conditions. Existing solutions also tend to be complex to implement, and/or consuming in terms of chip area.
There is thus a need for a variable capacitance device having a low step size and being relatively simple in terms of its implementation and layout.